Method of Evaluating Adhesion Property, Low-Adhesion Material, and Mold for Molding Resin

Abstract

A mold surface of an upper mold with which a fluid resin comes into contact has an oxide therein. The oxide contains a metal cation and an ion. Field strength is calculated based on a valence of the metal cation and ionic radius of the ion. Based on predetermined relationship established between a value of the field strength and adhesion strength between a cured resin and the mold surface, releasability between the cured resin and the mold surface is evaluated. Thereby, a method of evaluating releasability between the cured resin and the mold surface is established. With this evaluation method, a material with high releasability can readily be provided. Further, if the material with high releasability is used for the mold surface of the upper mold, a mold for molding a resin having excellent releasability can be obtained.

Description

TECHNICAL FIELD[0001]The present invention relates to a method of evaluating an adhesion property between an organic substance and a surface of a member, a low-adhesion material having a low adhesion property with respect to an organic substance, and a mold for molding a resin having a mold surface made of the low-adhesion material.BACKGROUND ART[0002]Conventionally, transfer molding or injection molding has been used for molding a resin. These techniques use a mold for molding a resin. The mold is provided with a resin flow channel and a cavity. A fluid resin is injected into the cavity through the resin flow channel. When the fluid resin in the cavity is cured, a cured resin is formed. As a result, a molded body having the cured resin is completed.[0003]A thermosetting resin is used as the fluid resin described above, and tool steel is used as a material for the mold. In this case, an adhesion property between the cured resin and the surface of the mold (mold surface) should be re...

AI Technical Summary

Benefits of technology

[0020]A method of evaluating an adhesion property of the present invention is a method of evaluating an adhesion property between an organic substance and a surface of a member having an oxide therein. In the method of evaluating an adhesion property of the present invention, a value of field strength is determined based on a valence of a metal cation (a positive metal ion) contained in the oxide and an ionic radius of an ion (including the metal cation) contained in the oxide, and the adhesion property is evaluated based on the value of the field strength. According to this method, the adhesion property between the organic substance and the surface of the member can be evaluated appropriately.

[0030]In the mold for molding a resin described above, it is desirable that the oxide includes Y2O3. Thereby, cost reduction in the mold for molding a resin can be achieved.

Problems solved by technology

However, the conventional technique described in the foregoing Japanese Patent Laying-Open No. 2004-25677 (on page 5 to page 6, and in FIGS. 1 and 2) has problems as described below.

Firstly, when the mold is made of a conventional material, a cured resin is likely to stick to a mold surface.

Therefore, frequent maintenance is required.

Secondly, numerous eject mechanisms are required to remove a molded body from the mold.

Thus, the mold becomes larger and has a complicated structure.

Thirdly, when the mold surface is coated with an organic material such as polytetrafluoroethylene or silicone rubber, these organic materials are likely to be worn by a filler contained in the fluid resin.

Therefore, it is difficult to use these organic materials singly as a material for reforming the mold surface.

Fourthly, when the mold surface is coated with an inorganic material with high hardness excellent in wear resistance such as Cr, TiC, or CrN, releasability between the cured resin and the mold surface is insufficient because these inorganic materials do not have a sufficient non-wetting characteristic with respect to a fluid resin.

Further, when the mold for molding a resin is made of a porous material, the range of selection for a material excellent in releasability is narrow.

Furthermore, there is a problem resulting from the fact that a method of evaluating releasability, in other words, a method of evaluating an adhesion property of a mold surface with respect to a cured resin has not been established.

As a physical factor of the change in the adhesion property, there is known a possibility that surface roughness is involved in the change.

However, a method of strictly evaluating an adhesion property between a cured resin and the surface of a member has not been established yet.

Therefore, in a conventional method of evaluating an adhesion property, samples of a plurality of oxides should be prepared and tested individually, and thus there is a problem that the method requires much time and effort.

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